Title

Bubble behavior and convection in frontal polymerization on the KC-135 aircraft

Document Type

Conference Proceeding

Publication Date

12-1-2000

Abstract

Frontal polymerization is a mode of converting monomer into polymer via a localized reaction zone that propagates through the coupling of thermal diffusion and Arrhenius reaction kinetics in an exothermic system. We studied two types of frontal polymerization systems on the KC-135 aircraft: The first is a liquid monomer producing a solid polymer with bubbles. Bubbles were larger in low g than in high g and were able to cause visible surface-tension induced convection ahead of the front. We observed a significant difference in the behavior of the fronts depending on the degree of conversion at which the solid formed. The second is a liquid monomer producing liquid polymer. Using the concept of the Korteweg stresses induced by concentration and temperature gradients, we show with numerical simulations that convection should occur in miscible systems with sharp but non-uniform concentration gradients, analogous to Surface-Tension Induced Convection in immiscible fluid layers. We attempted to observe such convection in low g caused by radial concentration gradients in propagating fronts of hexyl acrylate polymerization but because of the short time of low g and the g jitter, our results were inconclusive. We also studied a model system of miscillie fluids (glycerin/water) and observed droplet behavior similar to that in immiscible fluids. © 1999 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Publication Source (Journal or Book title)

38th Aerospace Sciences Meeting and Exhibit

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